As background for the invention, I will mention a few patents and then turn to other works which relate to products having some elements which may be relevant to a product made using my invention. U.S. Pat. No. 4,949,169, issued Aug. 14, 1990 to LUMELSKY, and assigned to International Business Machines Corp., describes an interface architecture for interconnecting a number of video display devices together over a high speed digital communication link having limited bandwidth. The interface architecture at each display node provides for transmitting sequential pixels of data composed of separate Y and C fields from a digital TV source in each node representative of a scaled video window. Audio information is transmitted with the video on portions of the network bandwidth not used by the video. It is an object of this invention to provide a hardware system which allows use of existing hardware in the various video display devices and associated communications adapters such that minimum additional control hardware and software is required.
U.S. Pat. No. 4,780,761, issued Oct. 25, 1988, to DALY et al and assigned to Eastman Kodak Company related to a device which recognizes that human visual system is less sensitive to diagonally oriented spatial frequencies than to horizontal or vertical ones. The transceiver has a way of quantifying the transform coefficients according to the model of the human vision system. This system is not designed to video conference workstations over the telecommunications network. It does not time share a video subprocessor as part of a audio/video communication processor and it does not function in a network control manner and hence cannot network.
U.S. Pat. No. 4,494,144, issued Jan, 15, 1985, to BROWN and assigned to AT&T describes a reduced bandwidth video transmission with good video presence. The bandwidth reduction is accomplished by dividing the video picture of the camera into segments by determining the activity level within each segment and by transmitting the signal of each segment with a resolution level which is related to the activity level within the segment. The most active segment is transmitted at the highest resolution while other segments are transmitted at lower resolutions. This system is not designed to video conference workstations over the telecommunications network. It does not time share a video subprocessor as part of a audio/video communication processor and hence cannot network.
U.S. Pat. No. 4,862,264, issued Aug. 29, 1989, to WELLS and assigned to British Broadcasting Corporation describes a method of coding a video signal for transmission in a restricted bandwidth by subdividing a frame of picture information into a set of constituent blocks, measuring the amount of picture activity in each block, sampling the information in each block at a rate related to the amount of picture activity in that block, and adding to the coded block a supplementary signal indicating the rate used for that block. A decision is made for each block to transmit at full accuracy or reconstruct it from the previous frame. In effect each block is sampled twice simultaneously. The first sampling is at a substrate and the second sampling is at the Nyquest rate. a block activity generator and motion activity generator are used to make decisions on transmitting the high accuracy or low accuracy. The samples may be transmitted in analog or digital form.
U.S. Pat. No. 4,654,484, issued Mar. 31, 1987, to REIFFEL and assigned to INTERAND CORP describes an improved apparatus for rapidly compressing, expanding and displaying broad band information which is transmitted over narrow band communications channel. A video image is cyclically assembled in low resolution and high resolution phases from digitized data representing gray level intensity for individual pixels which have been grouped into pixel. During the initial cycle of the low resolution phase, a representative sample of cell intensity values is transmitted by a sending station to a receiving station according to a video compression routine. The receiving station then used a video expansion routine to calculate an intensity value for those pixels whose intensity values were not transmitted and displays an initial image.
U.S. Pat. No. 4,682,225, issued Jul. 21, 1987 to GRAHM, and assigned to NASA, describes a method of, and apparatus for, telemetry adaptive bandwidth compression. An adaptive sampler from a video signal generates a sequence of sampled fields. Each field and it's range rate information are sequentially transmitted to and stored in a multiple adaptive field storage means. The patented apparatus may be used in spacecraft docking systems wherein vast amounts of video information and data must be transmitted in limited finite bandwidth. This invention is suited for space communication systems from a spacecraft of both video and data signals. In particular, a manual signal can control parameters such as range rate, sampling ratio, number of low resolution frames of video simultaneously displayed or portion of the down link communicati bandwidth allocated between data and video.
While this patent has little relationship with the preferred application of my invention, it will be noted that this sophisticated system may be significantly improved in my invention. During a video conference, a user may request reinitializing at any time. My communication processor also processes for recognition of degraded transmission data and automatic reinitializing. My communication processor controls reinitializing so as not to disrupt the existing channel bandwidth allocation among the users.
U.S. Pat. No. 4,739,413, issued Apr. 19, 1988 to MEYER, and assigned to LUMA TELECOM, describes a method of video optimized modulator demodulator with adjacent modulating amplitudes matched to adjacent pixel gray values. Each modulating symbol has a one to one correspondence with a particular pixel value of brightness. U.S. Pat. No. 3,795,763, issued Mar, 5, 1974 to GOLDING, and assigned to COMSAT CORP, describes a method of digital television transmission system for transmitting at substantially reduced bit rate and bandwidth. Frequency interleaving techniques reduce the sampling rate and digital differential PCM with edge recoding techniques reduce the number of bits per sample. Further reduction in bit rate is accomplished by eliminating about half the color data and all the sync pulses from the transmitted signal. Periodic sync words are transmitted to allow reconstruction of sync information. Transmitted bits are multiplexed in accordance with a particular format which provides proper alignment of the luminance and chrominance lines at the receiver. The Y & C are separated and sampled at less than the Nyquest rate. The samples are quantified and converted into difference samples having further bit reduction. The audio is sampled at the horizontal scan rate and the digital representations of audio and video are serially multiplexed into an output stream. Every other pair of C is completely eliminated from the multiplexed serial bit stream but is reconstructed at the receiver from adjacent C information.
U.S. Pat. No. 5,043,810, issued Aug. 27, 1991 to VREESWIJK, and assigned to US PHILIPS, describes a method of improved transmitting or recording an improved video signal processing apparatus and an improved receiving apparatus of a television signal. The method of processing is spatial and or temporal consistency control of a selection relating to spatially and or temporally neighboring parts of the image. The decision process includes neighboring parts of the image that may or may not have an effect on the part being processed. A block of pixels constitutes a part of the image and is sampled in accordance with a sampling pattern not corresponding to that operation and which block adjoins a block which is sampled with a sampling pattern corresponding to that operation, to the corresponding sampling pattern.
U.S. Pat. No. 4,720,745, issued Jan, 19, 1988 to DEFOREST, and assigned to DIGIVISION Inc., describes a method and apparatus for enhancing video displays. An NTSC composite video signal is dematrixed and its RGB components are digitized into a 512.times.512 frame pixel array. One high resolution frame is generated from each input frame. The subpixel values for a given pixel are derived by examining the nearest neighboring pixels and using enhancement algorithms represented by data in lookup tables. Signal to noise rations are handled by comparing and deciding to change the value of a pixel based on the value of the nearest neighbors or replace it with the median of it and its neighbors.
U.S. Pat. No. 4,858,026, issued Aug. 15, 1989 to RICHARDS, and assigned to US PHILIPS, describes a method of coding an image to be displayed. The image is coded using data compression which consists of first obtaining pixel information as a first matrix of high resolution. A second matrix of lower resolution is devised like the first through low pass filtering. A third matrix is the difference between the two. A fourth matrix is produced by sub-sampling the second matrix, (not every pixel is used). The third and fourth matrices are coded complementary decoding consists in restituting the second matrix and combining the restituted second matrix by interpolation filtering the decoded fourth matrix and combining the restituted second matrix with the decoded third matrix. This method has applications such as compact disk image encoding, but my communication processor does not work accord the principles set forth in this patent.
U.S. Pat. No. 4,733,299, issued Mar. 22, 1988 to GLENN, and assigned to NYIT, describes a method for conversion of interlaced scanned video signals to progressive scanned video signals. The applicant has learned that motion adaptive processing is not required. Low resolution information is obtained from the current interlaced field and the remaining detailed information is obtained from a stored signal that includes a prior field or fields. Only the detail signal is obtained from prior fields and since human vision does not as quickly perceive motion of high spatial frequencies, there will be little if any, perceived motion artifacts.
U.S. Pat. No. 4,551,755, issued Nov. 5, 1985 to MATSUDA, and assigned to PIONEER ELECTRIC CO, describes a method of bandwidth correcting system for a television tuner. A bandwidth control voltage is applied to a bandwidth adjusting circuit provides a passband width which is determined by the relative levels of a video intermediate frequency signal and an audio intermediate frequency signal. This patent seems to imply that the transmission process will over modulate, or exceed the allocated bandwidth for an instant from time to time and that a correcting signal will cause the receiver to recognize this condition and adjust.
The communication processor has a different application, process and method than described in U.S. Pat. No. 4,551,755. However the concept of bandwidth correcting and bandwidth allocation must be differentiated. A bandwidth allocation from video to voice or the reverse, does not necessarily need to be made and if it is made, it is not for the purpose to correct a malfunction such as over modulation, but rather to manage both types of bandwidth.
U.S. Pat. No. 4,792,993, issued Dec. 20, 1988 to MA, and assigned to CAPETRONIC (BSR) Ltd., describes a method of improved TVRO (TeleVision Receive Only, usually refers to TV by satellite). The improvement is in automatic filtering the audio signals to a frequency range of the band outside that of the modulated video signal, combining the filtered audio signals and the video signal and transmitting such signals through the restricted bandwidth channel. At the distant end the reverse process separates the signals into audio and video.
U.S. Pat. No. 4,849,811 issued Jul. 18, 1989 to KLEINERMAN and assigned to KLEINERMAN describes a method for simultaneously sending audio and video signals over standard telephone lines or other channel having restricted bandwidth which comprises obtaining a video image, digitizing the image, modulating a signal with the digitized image, obtaining audio signals and filtering the audio signals to a frequency range of the band outside that of the modulated video signal, combining the filtered audio signals and the video signal and transmitting such signals through the restricted bandwidth channel. At the distant end the reverse process separates the signals into audio and video.
The communication processor has some elements in common with this patent such a digitizing the video and processing it digitally, but it improves on it by combining the audio and video together into a continuous channel frame separated only by software protocol. U.S. Pat. No. 4,849,811 separates the audio and video in the restricted bandwidth frame by modulating the video and audio separately. The communication processor does not use a telephone channel. Instead, it uses a digital trunk, the smallest of which is 64,000 serial bits per second. The long distance carriers can provide this as trunk capacity or leased lines of which 64,000 serial bits per second provides minimal video conferencing service. Best performance is obtained with high bandwidth network carriers.
U.S. Pat. No. 4,425,642, issued Jan. 10, 1984 to MOSES, and assigned to APP SPEC TECH Inc., describes a method of co-channel communications system which permits a digital data signal to be simultaneously transmitted within a communications medium signal such a telephone voice or television video. The data signals are converted to very low multifrequency signals consisting of fundamental frequencies and harmonics which span the communications bandwidth. The data signal is spread spectrum modulated, its energy content is spread over the entire band causing a small degradation in signal to noise by adding what appears to be pseudo noise to the audio or video signal. Since the data signals coherently produce the pseudo noise it is detected coherently and removed from the audio or video at the receiver.
The communication processor does not perform spread spectrum modulation, nor does co-channel data with voice or video. Rather the communication processor uses a protocol to keep audio, video, and data in a serial transmission channel.
U.S. Pat. No. 3,873,771, issued Mar. 25, 1975 to KLEINERMAN, and assigned to TELSCAN, describes a system for simultaneously transmitting a video and audio signal through the same transmission line using FM slow scan TV while the audio signal is transmitted by AM single sideband technique. Both the video and audio occupy the channel at the same time in separate frequency regions. My communication processor need not use any analog modulation techniques, or frequency multiplexing techniques or slow scan FM TV techniques.
U.S. Pat. No. 4,797,750, issued Jan. 10, 1989 to KARWEIT, and assigned to J. HOPKINS U., describes a method and apparatus for transmitting a recorded computer generated display simultaneously with the transmission of audio and or video signals. A computer generates a series of codes from which an image may be derived, the resolution of which is not dependent on the recording transmission medium. These codes are supplied to a first modem through an RS-232 communications line. The first modem converts these codes to into image bearing audio tones. The audio tones are input in the left audio channel of a video recorder. Simultaneously, aural information is picked up by a microphone and input into the right audio channel while a video camera provides video signals to the video channel of the recorder. On playback the audio in the left channel is decoded by the modem and reconverted back to computer generated display. My communication processor does not perform spread spectrum modulation, nor do use a RS-232 communications line. Instead, I illustrate a different kind of use of a modem.
U.S. Pat. No. 4,736,407, issued Apr. 5, 1988 to DUMAS, and assigned to US ARMY, describes a method of audiographic conferencing system between two or more users either directly connected or through a bridging device over voice grade telephone lines. Each user has a personal computer, software and a smart modem, cassette player/recorder and speaker phone. They are connected as shown in FIG. 1. The smart modems listen for a bauded signal, if present decode it and pass it to the computer, the speaker phone allows the user to listen to speech while being under software control. The cassette recorder/player is used for unattended operation.
The communication processor differs from this patent in that video conferencing performed by this patent, rather computer data and voice is conferenced.
U.S. Pat. No. 4,955,048, issued Sep. 4, 1990 to IWAMURA, and assigned to SHARP Kabushiki Kaisha, describes a method for multiplexing the transmission of audio and video signals, the video signal is separated into a luminance (Y) and a chrominance (C) signal. The Y signal is then modulated and the C signal is balanced modulated with a low frequency carrier. The resultant C modulated signal is converted to a lower frequency. The audio signal, frequency modulated Y signal and frequency converted C signal are multiplied by frequency division to be transmitted across a telephone cable.
U.S. Pat. No. 4,999,831, issued Mar. 12, 1991 to GRACE, and assigned to UNITED TELCOMM Inc, describes a method of digital transmission of wideband video, narrowband audio, and digital information over information networks. It describes synchronous quantitized subcarrier multiplexing which results in electronic multiplexing of voice, data and multiple channel full bandwidth NTSC video for digital transmission over communication line and recovery processing. The channels to be multiplexed must be carefully chosen for frequency content so as not to interfere with each other, then the signals are low pass filtered and modulated with local reference signals (Double Side Band Suppressed Carrier DSBSC) and consequently form baseband, midband and high band channels which are combined and input into a D/A converter. This results in a serial bit stream known as quantitized-SCM. This patent is unlike the present invention.
U.S. Pat. No. 5,027,400, issued Jun. 25, 1991 to BAJI, and assigned to HITACHI Ltd, describes a multimedia bidirectional broadcast system. The main control unit receives information over a network from subscriber stations. Software in the main unit decodes the request from the subscriber station and provides the service by controlling all transmission processes. The service may be a motion picture or a commercial data base. Transmission also includes bandwidth compression on a video signal. This system is described as providing a broadband ISDN broadcast system, and to provide CATV with means for using a limited number of cable channels.
My communication processor differs from this patent in that the patent is designed for interactive advertising on ISDN broadband networks where shoppers can see video images of the product and interact with the master station to perform transactions. This patent is also applicable to CATV systems where customers can order video programming services selectively rather than having technicians hard wire customer requested programming services. My communication processor intended to do workstation video conferencing.
U.S. Pat. No. 4,541,008, issued Sep. 10, 1985 to FISHMAN, and assigned to JONES FUTURA FOUNDATION Ltd., describes a television signal transmission system incorporating circuits for processing and encoding a repetition reduced signal. The system separates the video components and generates sampled digital values of the color, intensity components and puts them in a storage buffer. A data processor compares successive samples of the component video data from which it generates variable length blocks of video data to represent slowly varying signals or rapidly varying signals. There is circuitry for encoding and multiplexing audio and synchronizing data into the signal stream, circuitry for encoding signal and control data for transmission to a receiver and a circuit at the receiver for reversing this process. The process of reducing repetition is to use variable velocity scanning by using codes to indicate when color, intensity, and luminance information is repeatable. When information is repeatable, only every eighth sample is transmitted. Timing information to control the scan rate is crucial. The orderly progression of the line scan now depends on circuits to make up the rate tag with interpolation data. My communication processor on the other hand reduces repetitious video data.
U.S. Pat. No. 4,394,774, issued Jul. 19, 1983 to WIDERGREN, and assigned to COMPRESSION LABS Inc, describes a method of digital video compression and expansion system and the methods for compressing and expanding digital video signals in real time at rates up to NTSC color broadcast rates. The system compressor receives digital frames and divides them into subframes, performs a single pass spatial domain to transform domain transformation in two dimensions of picture elements. The resultant coefficients are normalized and compressed using a predetermined ratio. There is an adaptive rate buffer to control feedback for compression. The compressor adaptively determines the rate buffer capacity control feedback component in relation to instantaneous data content of the rate buffer memory in relation to its capacity, and it controls the absolute quantity of data resulting from the normalization step so the buffer is never empty or full. In practice, the color picture is divided into luminance, and I and Q chrominance components. The luminance component is compressed and expanded with the scene adaptive coding rate buffer feedback technique. The I and Q components are given simple spatial low pass filtering followed by spatial subsampling with dimensional interpolation at the system receiver. The audio is filtered and sampled at a fixed rate and muxed together with bit screen synchronization codes and transmitted as a serial bit stream.